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Institutes/ Institute of life sciences research and technologies (iRTSV)/ Unités / Chimie et Biologie des Métaux (CBM)/ Jobs opportunities

Jobs opportunities



Two-years Post doctoral position (Beginning November-December 2011)
 

In the last decades, as a consequence of the inevitable end of fossil energy resources associated with a high increase in energy consumption, attempts to develop sustainable energies have emerged all over the word. As a consequence, tremendous efforts were made to take advantage of the exceptional photophysical properties of ruthenium polypyridyl complexes with the final objective to convert solar energy into chemical energy. In our research program aiming to develop new polypyridyl ruthenium-based catalysts for oxidation, we were interested in the combination of a photosensitizer and a catalytic fragment within the same complex to achieve catalytic light-driven oxidation. As far as we know, only one paper, published two years ago, reported the application of such a system for alcohol oxidation (Rocha et al. Angew. Chem. Int. Ed., 2009, 48: 9672). However, on the contrary to the alcohol oxidation which requires “only” a proton-coupled electron transfer (PCET), sulfides, alkenes and alkanes oxidation requires also an oxygen atom transfer. Due to the lack in such a field, we reported very recently a new eco-aware catalytic system able to perform the oxidation of sulfides via an oxygen atom transfer from H2O to the substrate (Hamelin et al. Inorg. Chem., 2011, 50: 7952)

In this proposal, we envisage to introduce a third properties of octahedral ruthenium complexes, still poorly exploited, that is to say their particular kind of chirality (Chirality Δ-Λ) in order to develop new “eco-aware” methods for asymmetric catalytic light-driven oxidation using water as the unique oxygen atom source.
The originality of the proposed project relies on four main points:

i) Water, as an abundant and non-toxic molecule, will be used as the unique oxygene atom source,
ii) Whereas all the metal-dependant asymmetric catalyses involve chiral organic ligands, in this project, the metal will be the unique stereogenic center. This will be our priority. However, the use of chiral organic ligands will also be explored.
iii) The photosensitizer, the chiral inducer and the catalytic center will be associated within a unique catalyst.
iv) Solar (light) energy will be converted into chemical energy.

Consequently, this project involves the synthesis of chiral dyads or bimolecular systems, their full characterization (electrochemistry, UV-visible spectroscopy, NMR, circular dichroism…). Their catalytic activity will then be evaluated during asymmetric oxygenation of organic substrates (sulfides, alkenes, alkanes). At the same time, photophysical studies of the synthesized systems will be performed in the group of our collaborator (Pr. Frédérique Loiseau) in order to i) highlight the required electron transfer between all the partners to achieve the photocatalytic oxygenation, ii) determine the appropriate structural and electronic modifications to achieved on the ligands to optimize the catalytic activity.

  Dr. Olivier Hamelin
 CEA Grenoble
17 avenue des Martyrs
38 054 Grenoble Cedex 09
Tel. : (33) 4 38 78 91 08
Fax : (33) 4 38 78 91 24


Proposal for a funded thesis co-directed with LPCV
 

Metal homeostasis in chloroplasts: comparative study of three transporters belonging to the PIB-type ATPases family
Involved in many cellular processes, transition metals like u+, Mn2+ or Zn2+ are essential for plant development. In Arabidopsis thaliana, three transporters of the PIB-type ATPase family are required for copper delivery to chloroplast and thylakoïds: HMA6, HMA8 and HMA1 whose ionic selectivity is still controversial. So far, the role of these proteins has only been deduced from genetics; the difficulty to obtain active forms of these transporters either from their native environment or from heterologous expression preventing any biochemical approach. Recently, we have shown that Lactococcus lactis was well suited for the production of these ATPases and demonstrated biochemically that HMA6 was a high affinity Cu(I) transporter.
The aim of this project is to characterize in details the chloroplastic ATPases HMA1, 6 and 8 by both biochemical and structural approaches. To reach this goal, native and mutated forms of the transporters will be first produced in L. lactis. Their enzymatic properties will be further determined by phosphorylation assays previously setup for HMA6 study. The collected informations will allow a comparison of the functional charcteristics of the three HMAs in terms of ionic specificity, affinity for metals and ATP and will also reveal aminoacids or domains essential for their activity. In parallel, HMA6 will be purified in an active form and in large amount, prerequisits for the structural study of this transporter.
Our results should improve our knowledge of plant PIB-type ATPases and provide new informations on the molecular mechanisms that occur during metal transport by these proteins. Together with the data coming from in planta studies, they should also allow to specify the relative role of HMA1, 6 and 8 in the metal homeostasis of chloroplast.

Funding:
co-funding by CEA/labex Gral

From:
Septembre 2012 to Septembre 2015

Lab:
Institut de Recherche en Technologies et Sciences pour le Vivant
Laboratoire de Physiologie Cellulaire & Végétale,
D-Phy-Chloro team
CEA Grenoble
and
Laboratoire Chimie et Biologie des Métaux
Biomet team
CEA Grenoble

Contacts:
Daphné Seigneurin-Berny
Laboratoire de Physiologie Cellulaire & Végétale
UMR 5168 CNRS/UJF/INRA/CEA-Grenoble
iRTSV - 17 rue des Martyrs
38 054 Grenoble cedex
Phone: 33 (0)4 38 78 23 63

Patrice Catty
Laboratoire Chimie et Biologie des Métaux
UMR 5249 CNRS/UJF/CEA-Grenoble
iRTSV - 17 rue des Martyrs
38 054 Grenoble cedex
Phone: 33 (0)4 38 78 93 05

Other informations:
Training in molecular biology and biochemistry desired.
The candidate must have an honors master 2.